Varnish4.1.2配合FastDFS构建内存缓存

栏目：框架设计时间：2016-08-17 09:55:29

Varnish是甚么

Varnish是1款高性能的开源HTTP加速器，挪威最大的在线报纸 Verdens Gang (http://www.vg.no) 使用3台Varnish代替了原来的12台squid，性能竟然比之前更好。

Varnish 的作者Poul-Henning Kamp是FreeBSD的内核开发者之1，他认为现在的计算机比起1975年已复杂许多。在1975年时，贮存媒介只有两种：内存与硬盘。但现在计算机系统的内存除主存外，还包括了cpu内的L1、L2，乃至有L3快取。硬盘上也有自己的快取装置，因此squid cache自行处理物件替换的架构不可能得知这些情况而做到最好化，但操作系统可以得知这些情况，所以这部分的工作应当交给操作系统处理，这就是 Varnish cache设计架构。
【以上摘自http://www.oschina.net/p/varnish】

开始

空话说完了，接下来就是怎样使用它了。本文描写的内容基于Varnish 4.1.2版本。

安装Varnish：

（1）源码安装
下面这个是Varnish的官网：https://www.varnish-cache.org/
github的地址：https://github.com/varnishcache/varnish-cache
下载下来源码包，进行编译安装。
（2）命令安装
在官网上可以看到说明：
https://www.varnish-cache.org/releases/install_ubuntu.html#install-ubuntu

apt-get install apt-transport-https
curl https://repo.varnish-cache.org/GPG-key.txt | apt-key add -
echo "deb https://repo.varnish-cache.org/ubuntu/ trusty varnish⑷.1" \
     >> /etc/apt/sources.list.d/varnish-cache.list
apt-get update
apt-get install varnish

可以看到，通过命令行直接安装比较方便。

配置Varnish

这1点还是值得注意的，我在配置的时候，发现网上大部份文档都是之前的版本，但是在4.x版本以后，配置方式产生了变化，也折腾了些时间，所以，希望能帮助你跳过坑。

Varnish运行参数配置

默许的端口是监听6081，你怎样知道？
看这个文件：

vi /etc/default/varnish

tfxiaozi@server:~$ cat /etc/default/varnish
# Configuration file for Varnish Cache.
#
# /etc/init.d/varnish expects the variables $DAEMON_OPTS, $NFILES and $MEMLOCK
# to be set from this shell script fragment.
#
# Note: If systemd is installed, this file is obsolete and ignored.  You will
# need to copy /lib/systemd/system/varnish.service to /etc/systemd/system/ and
# edit that file.

# Should we start varnishd at boot?  Set to "no" to disable.
START=yes

# Maximum number of open files (for ulimit -n)
NFILES=131072

# Maximum locked memory size (for ulimit -l)
# Used for locking the shared memory log in memory.  If you increase log size,
# you need to increase this number as well
MEMLOCK=82000
DAEMON_OPTS="-a :6081 \
             -T localhost:6082 \
             -f /etc/varnish/default.vcl \
             -S /etc/varnish/secret \
             -s malloc,24G"
tfxiaozi@server:~$

没错啦，就是这里，Varnish运行时占用了6081端口，6082用作管理。

-a 如果希望使用80端口直接访问，修改成80便可  
-s 使用的内存大小
-S 认证的密钥文件 varnishadm -T localhost:6082 -S secret
-f 指定了Varnish运行起来时需要加载的配置文件，用来管理后端服务器

Varnish 密钥文件

在上面的配置中可以看到，密钥文件在/etc/varnish下。

访问http://varnish_VPS_public_IP:6081，前面是Varnish安装的机器ip，此时会出现503访问毛病，缘由是没有配置后端要cache的服务器。

配置后端web服务器

这里以后端FastDFS存储集群机器为例进行配置，目的是让Varnish对FastDFS的Storage节点进行缓存，以下降直接访问Storage节点酿成的压力。
Storage1: 10.10.10.81;
Storage2: 10.10.10.82.
给出详细的配置文件：

root@server:/etc/varnish# cat default.vcl 
#
# This is an example VCL file for Varnish.
#
# It does not do anything by default, delegating control to the
# builtin VCL. The builtin VCL is called when there is no explicit
# return statement.
#
# See the VCL chapters in the Users Guide at https://www.varnish-cache.org/docs/
# and https://www.varnish-cache.org/trac/wiki/VCLExamples for more examples.

# Marker to tell the VCL compiler that this VCL has been adapted to the
# new 4.0 format.
vcl 4.0;

import std;
import directors;
# Default backend definition. Set this to point to your content server.
#backend default {
#    .host = "127.0.0.1";
#    .port = "8080";
#}

#probe healthcheck {
#   .url = "/";
#   .interval = 6s;
#   .timeout = 1s;
#   .window = 5;
#   .threshold = 3;
#}

backend fdfs_g1_s1 {
     .host = "10.10.10.81";
     .port = "10000";
#     .probe = healthcheck;     #健康状态检测
}

backend fdfs_g1_s2 {
     .host = "10.10.10.82";
     .port = "10000";
#    .probe = healthcheck;     #健康状态检测
}

acl purgers {
    "localhost";
    "127.0.0.1";
}

sub vcl_init {
    new vdir = directors.round_robin();
    vdir.add_backend(fdfs_g1_s1);
    vdir.add_backend(fdfs_g1_s2);
    return (ok);
}


sub vcl_recv {
     # Happens before we check if we have this in cache already.
     #
     # Typically you clean up the request here, removing cookies you don't need,
     # rewriting the request, etc.
     set req.backend_hint = vdir.backend();
     if (req.http.x-forwarded-for) {
         set req.http.X-Forwarded-For = req.http.X-Forwarded-For + ", " + client.ip;
     } else {
         set req.http.X-Forwarded-For = client.ip;
     }    

     if (req.method == "PURGE") {    # PURGE要求的处理
        if (!client.ip ~ purgers) {
            return(synth(405,"Method not allowed"));
        }
        #清算缓存
        return (purge);
     }
     # 制止缓存的文件
     if (req.url ~ "\.(php|jsp|do)($|\?|#)") {
        return (pass);
     }

     if (req.method == "PRI") {
        #/* We do not support SPDY or HTTP/2.0 */
        return (synth(405));
     }
     if (req.method != "GET" &&
       req.method != "HEAD" &&
       req.method != "PUT" &&
       req.method != "POST" &&
       req.method != "TRACE" &&
       req.method != "OPTIONS" &&
       req.method != "DELETE") {
         #/* Non-RFC2616 or CONNECT which is weird. */
         return (pipe);
     }

     if (req.method != "GET" && req.method != "HEAD") {
         #/* We only deal with GET and HEAD by default */
         return (pass);
     }
     if (req.http.Authorization || req.http.Cookie) {
         #/* Not cacheable by default */
         return (pass);
     }
     return (hash);
}

sub vcl_backend_response {
    # Happens after we have read the response headers from the backend.
    #
    # Here you clean the response headers, removing silly Set-Cookie headers
    # and other mistakes your backend does.
    if (bereq.url ~ "^[^?]*\.(7z|avi|bmp|bz2|css|csv|doc|docx|eot|flac|flv|gif|gz|ico|jpeg|jpg|js|less|mka|mkv|mov|mp3|mp4|mpeg|mpg|odt|otf|ogg|ogm|opus|pdf|png|ppt|pptx|rar|rtf|svg|svgz|swf|tar|tbz|tgz|ttf|txt|txz|wav|webm|webp|woff|woff2|xls|xlsx|xml|xz|zip)(\?.*)?$") {
        unset beresp.http.set-cookie;
    }    
    # Large static files are delivered directly to the end-user without
    # waiting for Varnish to fully read the file first.
    # Varnish 4 fully supports Streaming, so use streaming here to avoid locking.
    if (bereq.url ~ "^[^?]*\.(7z|avi|bz2|flac|flv|gz|mka|mkv|mov|mp3|mp4|mpeg|mpg|ogg|ogm|opus|rar|tar|tgz|tbz|txz|wav|webm|xz|zip)(\?.*)?$") {
       unset beresp.http.set-cookie;
       set beresp.do_stream = true;  # Check memory usage it'll grow in fetch_chunksize blocks (128k by default) if the backend doesn't send a Content-Length header, so only enable it for big objects
       set beresp.do_gzip   = false;   # Don't try to compress it for storage
    }
    # Set 2min cache if unset for static files
    if (beresp.ttl <= 0s || beresp.http.Set-Cookie || beresp.http.Vary == "*") {
      set beresp.ttl = 120s; # Important, you shouldn't rely on this, SET YOUR HEADERS in the backend
      set beresp.uncacheable = true;
      return (deliver);
    }
    # Allow stale content, in case the backend goes down.
    # make Varnish keep all objects for 6 hours beyond their TTL
    set beresp.grace = 6h;

    return (deliver);
}


sub vcl_backend_fetch {
    return (fetch);
}

sub vcl_pipe {
     # By default Connection: close is set on all piped requests, to stop
     # connection reuse from sending future requests directly to the
     # (potentially) wrong backend. If you do want this to happen, you can undo
     # it here.
     # unset bereq.http.connection;
     return (pipe);
}

sub vcl_pass {
     return (fetch);
}

sub vcl_hash {
     hash_data(req.url);
     if (req.http.host) {
         hash_data(req.http.host);
     } else {
         hash_data(server.ip);
     }
     return (lookup);
}

sub vcl_purge {
     return (synth(200, "Purged"));
}

sub vcl_hit {
     if (obj.ttl >= 0s) {
         #// A pure unadultered hit, deliver it
         return (deliver);
     }
     if (obj.ttl + obj.grace > 0s) {
         #// Object is in grace, deliver it
         #// Automatically triggers a background fetch
         return (deliver);
     }
     #// fetch & deliver once we get the result
     return (miss);
}

sub vcl_miss {
     return (fetch);
}

sub vcl_deliver {
    set resp.http.x-hits = obj.hits;
    if (obj.hits > 0) {
        set resp.http.X-Cache = "Hit varnish cache";
    }else {
        set resp.http.X-Cache = "Miss varnish cache";
    }
    return (deliver);
} 

sub vcl_synth {
     set resp.http.Content-Type = "text/html; charset=utf⑻";
     set resp.http.Retry-After = "5";
     synthetic( {"<!DOCTYPE html>
 <html>
   <head>
     <title>"} + resp.status + " " + resp.reason + {"</title>
   </head>
   <body>
     <h1>Error "} + resp.status + " " + resp.reason + {"</h1>
     <p>"} + resp.reason + {"</p>
     <h3>Guru Meditation:</h3>
     <p>XID: "} + req.xid + {"</p>
     <hr>
     <p>Varnish cache server</p>
   </body>
 </html>
 "} );
     return (deliver);
}


sub vcl_backend_error {
     set beresp.http.Content-Type = "text/html; charset=utf⑻";
     set beresp.http.Retry-After = "5";
     synthetic( {"<!DOCTYPE html>
 <html>
   <head>
     <title>"} + beresp.status + " " + beresp.reason + {"</title>
   </head>
   <body>
     <h1>Error "} + beresp.status + " " + beresp.reason + {"</h1>
     <p>"} + beresp.reason + {"</p>
     <h3>Guru Meditation:</h3>
     <p>XID: "} + bereq.xid + {"</p>
     <hr>
     <p>Varnish cache server</p>
   </body>
 </html>
 "} );
     return (deliver);
}

sub vcl_fini {
     return (ok);
}

默许情况下，如果只有1台机器做web server，使用backend default进行配置便可。如果是多台机器提供相同的内容服务，那末可以将多个web server进行组管理，通过robin轮询或random提供服务，具体要注意的细节：
①自定义后台server

backend fdfs_g1_s1 {
     .host = "10.10.10.81";
     .port = "10000";
#     .probe = healthcheck;     #健康状态检测
}

backend fdfs_g1_s2 {
     .host = "10.10.10.82";
     .port = "10000";
#    .probe = healthcheck;     #健康状态检测
}

②初始化

sub vcl_init {
    new vdir = directors.round_robin();
    vdir.add_backend(fdfs_g1_s1);
    vdir.add_backend(fdfs_g1_s2);

    return (ok);
}

初始化操作放到init中便可。
③然后，需要在vcl_recv中进行设置当前使用的backend，

set req.backend_hint = vdir.backend();

做完这3步，varnish就配置好了，固然还可以根据需要配置节点健康检查。

启动Varnish

履行以下命令：

service varnish start

可以通过netstat -unltp | grep varnish 查看当前端口是不是被varnish占用：

root@server:/etc/varnish# netstat -unltp | grep varnish
tcp        0      0 0.0.0.0:6081            0.0.0.0:*               LISTEN      26565/varnishd  
tcp        0      0 127.0.0.1:6082          0.0.0.0:*               LISTEN      26565/varnishd  
tcp6       0      0 :::6081                 :::*                    LISTEN      26565/varnishd  
tcp6       0      0 ::1:6082                :::*                    LISTEN      26565/varnishd

测试

既然配置好了，那末就改测试1下，看看效果怎样样了。
Storage1: 10.10.10.81;
Storage2: 10.10.10.82;
我这里varnish装在192.168.165.21机器上，配置了双网卡。
这里写图片描述
可以看到，当访问6081端口时，出现了nginx的界面，这是由于在FastDFS配置了Storage使用Nginx提供http服务，也就是说当前配置到后端服务器是OK了。

下面来测试1下缓存到底有无起作用？
第1次：

Request URL:http://192.168.165.21:6081/group1/M00/00/00/CgoK0ldybhOAYFAfAAAOelbujmQ479.png
Request Method:GET
Status Code:200 OK
Remote Address:192.168.165.21:6081
Response Headers
view source
Accept-Ranges:bytes
Age:0
Connection:keep-alive
Content-Length:3706
Content-Type:image/png
Date:Tue, 28 Jun 2016 12:31:56 GMT
Last-Modified:Tue, 28 Jun 2016 12:31:15 GMT
Server:nginx/1.8.1
Via:1.1 varnish-v4
X-Cache:Miss varnish cache
x-hits:0
X-Varnish:98311
Request Headers
view source
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Encoding:gzip, deflate, sdch
Accept-Language:zh-CN,zh;q=0.8
Connection:keep-alive
DNT:1
Host:192.168.165.21:6081
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.109 Safari/537.36

可以看到，第1次没有再缓存中命中：X-Cache:Miss varnish cache

第2次：

Request URL:http://192.168.165.21:6081/group1/M00/00/00/CgoK0ldybhOAYFAfAAAOelbujmQ479.png
Request Method:GET
Status Code:200 OK
Remote Address:192.168.165.21:6081
Response Headers
view source
Accept-Ranges:bytes
Age:16
Connection:keep-alive
Content-Length:3706
Content-Type:image/png
Date:Tue, 28 Jun 2016 12:31:56 GMT
Last-Modified:Tue, 28 Jun 2016 12:31:15 GMT
Server:nginx/1.8.1
Via:1.1 varnish-v4
X-Cache:Hit varnish cache
x-hits:1
X-Varnish:13 98312
Request Headers
view source
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Encoding:gzip, deflate, sdch
Accept-Language:zh-CN,zh;q=0.8
Cache-Control:max-age=0
Connection:keep-alive
DNT:1
Host:192.168.165.21:6081
If-Modified-Since:Tue, 28 Jun 2016 12:31:15 GMT
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.109 Safari/537.36

可以看到，第2次命中：X-Cache:Hit varnish cache。

清算缓存

配置文件指定了PURGE和IP 就能够用curl 清算缓存

root@server:/etc/varnish# curl -X PURGE http://127.0.0.1:6081/group1/M00/00/00/CgoK0ldybhOAYFAfAAAOelbujmQ479.png     
<!DOCTYPE html>
 <html>
   <head>
     <title>200 Purged</title>
   </head>
   <body>
     <h1>Error 200 Purged</h1>
     <p>Purged</p>
     <h3>Guru Meditation:</h3>
     <p>XID: 98320</p>
     <hr>
     <p>Varnish cache server</p>
   </body>
 </html>
 root@server:/etc/varnish#

1些命令

①varnishstat
可以查看缓存命中率
缓存命中率的高低，直接反应Varnish的运行状态，以下通过varnishstat命令查看状态信息：
这里写图片描述
Hitrate n 第1个数字范围0⑴0，第2个数字范围0⑴00，第3个数字范围0⑴000。分别表示过去N秒内的
avg(n) 里的内容是命中率，需要乘以100转换成百分比。
②varnishlog
可以查看实光阴志。

附录

1篇英文文档
https://www.digitalocean.com/community/tutorials/how-to-configure-varnish-cache⑷-0-with-ssl-termination-on-ubuntu⑴4-04
github上1篇关于4.0的详细配置模板：
https://github.com/mattiasgeniar/varnish⑷.0-configuration-templates/blob/master/default.vcl
1篇关于之前低版本的配置，里面讲了关于Varnish性能优化和varnishadm 命令。
http://xiaodong88.blog.51cto.com/1492564/1304988

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